If you are trying to post an image and it is showing up sideways on the forum there is a very simple fix.

1. Open the image on your PC (for example in Windows 10 use the "Photos" program)
2. Make sure the orientation on the screen is correct and make any small change to the image - like crop it or change the brightness/ contrast by a small bit.
3. Save the image and upload that image to the forum. The orientation should now be correct.